I have seen a lot of posts relating to the use of parametric dimensions being applied to boxes, where finger joints are being adjusted to compensate for change in material dimensions etc.,

but I’m looking for the use of mathematical formulae in laying out curved lines (ie parabolic curves).

I’ve used this when designing for my cnc router, with a program called Axis, inside linuxcnc, and writing my own gcode for it.

If anyone onboard is familiar with this, I’d be grateful to know if this sort of approach, the maths, not gcode, is possible in the common vector software that is discussed here.

John

# Parametric curves

**johnbrooker**#1

**palmercr**#2

If you use OpenSCAD you can describe anything mathematically, in fact that is the only way. I export DXF and use PyCAM to make GCODE for Axis. For GlowForge I will export SVG.

Fusion 360 claims to be fully parametric and everything I’ve tried it for is but I’ve never tried laying down complex curves so I don’t know how you would approach it.

I would think that you would pick an existing curve type and define it with a formula.

**mpipes**#4

Fusion360 does have the maths for parabolic curves. I have not used this function yet, but it is there.

**johnbrooker**#5

Thanks for that idea.

I’ve taken a quick look at the description, and it looks like software that I can get into fairly quickly.

For GlowForge I will export SVG.

I normally use an old version of CorelDraw as my drawing program. Do you see any problems I might have in integrating the two, ie moving vectors drawn in OpenSCAD into Corel ?

John

**palmercr**#6

OpenSCAD currently has no control over the colour, stroke and fill when exporting to SVG but the polygons it produces should import into other programs.

**johnbrooker**#7

Thanks for the heads up.

Another way for me to try, if OpenSCAD becomes problematic for me.

John

EDIT Fusion doesn’t work on my system, it tells me. Probably as I’m trying to download it on my ubuntu 32bit machine, but want to install it on a different one - XP 32bit.

**henryhbk**#8

OnShape also has conic curves as well as a full scripting language like OpenSCAD. I do occasionally use openscad but I find the ability to mix regular sketch based cad modeling with programatic is way more powerful.

**paulw**#9

If you’re going through inkscape or some other program from Openscad, you might find it worthwhile to export as dxf instead of SVG. Counterintuitive, I know, but in a few cases I’ve had an easier time dealing with the grouping.

**johnbrooker**#11

That’s the one !

Already got it installed, and have some familiarity with it, so that’s good.

Your screen shot shows me exactly what I need in one step.

Many thanks

John